Heat storage pack, cold storage pack, logistic packaging container, logistic system, and logistic method

ABSTRACT

A heat or cold storage pack is provided that contains a latent thermal storage material that can be restored during transport to prolong a heat or cold storage function thereof and that exhibits a reduced temperature change in a phase transition thereof to reliably maintain the temperature of an object to be kept warm or cold in a temperature range in which the object should be kept. The heat storage pack is for use in a logistic packaging container to adjust the temperature of an object to be kept warm and includes: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept warm should be kept in such a manner that the solidification temperature is in the temperature range in which the object to be kept warm should be kept and that the onset temperature of melting is lower than an upper limit of the temperature range in which the object to be kept warm should be kept.

TECHNICAL FIELD

The present invention relates to heat storage packs, cold storage packs, logistic packaging containers, logistic systems, and logistic methods using a latent thermal storage material.

BACKGROUND ART

Wealthy modern lifestyles are supported by logistic systems and services in which, for example, food articles, medicines, and electronic components are transported while being kept at predetermined temperatures all the way from a consignor to a consignee for the purpose of maintaining them fresh and/or preserving their quality.

In such an isothermal logistic system, transported goods are typically packaged in an adiabatic box to restrict heat exchange between the transported goods and the environment. A thermal or cold storage material, which releases or absorbs heat, is packaged together during transport as a preparation against an increased inflow or outflow of heat that may occur due to a large temperature difference from ambient temperature.

Goods are rarely delivered directly from a consignor to a consignee in current isothermal logistic systems. They are often transported via hubs for various reasons including the control of transport schedules and the inspection and sorting of goods. The temperature of the goods needs to be controlled also at these hubs. The goods are temporarily stored in a facility that offers an electrical heat/cold storage function such as a refrigerated warehouse. If the transport takes a long time, for example, from the consignor to the hub, the goods are transported in a vehicle having an electrical heat/cold storage function.

Conventional logistic systems have paid attention to the temperature at which a thermal storage material releases or absorbs heat and the holding temperature during transport and at the hubs in view of the temperatures at which the goods should be maintained. No conventional systems have however paid attention to thermal storage materials and temperature during transport and at the hubs.

Consequently, thermal storage materials may waste their energy by releasing or absorbing heat in an undesirable manner during transport or at the hubs. The thermal storage material may need to be increased in quantity or replaced at the hub, which requires undesirable additional cost.

Patent Literature 1 discloses a cooling container including a cooling container main body for containing an article and a refrigerator for cooling the inside of the cooling container. The refrigerator is structured so as to allow a cold storage material composed of a fluid having a refrigerating function to be freely taken out of, and put into, the refrigerator. Each transport hub has a cold storage material exchanger. The technology reduces the time required to cool the cooling container sufficiently.

Patent Literature 2 discloses a method that enables an article that needs to remain refrigerated to be maintained throughout transport at above-zero refrigeration temperatures required during cold transport without using a refrigerator. The technology involves placing the article and a cold storage material in a cooling box, precooling (but not freezing) a first cold storage body at above-zero temperatures, and disposing a thermal storage material and the first cold storage body between a frozen second cold storage body and the article.

CITATION LIST Patent Literature Patent Literature 1: Japanese Unexamined Patent Application Publication, Tokukai, No. 2001-66028 Patent Literature 2: Japanese Unexamined Patent Application Publication, Tokukai, No. 2005-300052 SUMMARY OF INVENTION Technical Problem

The technology disclosed in Patent Literature 1 necessitates replacing the cold storage material at the hubs. Transport routes are seriously restricted because the routes need to include the hubs where a cold storage material exchanger is available. In addition, the cold storage material is a fluid and stores thermal energy in the form of sensible heat which only comes in extremely small amounts. The cold storage material therefore needs to be replaced at every hub.

The technology disclosed in Patent Literature 2 uses cold storage bodies with a melting temperature lower than the temperature of the article that needs to remain refrigerated. The article may be transported via a cool warehouse, but temperature in the warehouse is inevitably set higher than the melting temperature of the cold storage bodies, which promotes melting of the cold storage bodies. Long-hour transport therefore is not feasible without carrying a large quantity of cold storage body in the transport vehicle. This requirement reduces the volume reserved for the article that needs to remain refrigerated in relation to the capacity of the packaging container. Similar problems are found with thermal storage, where the thermal storage material needs to be replaced at every hub and requires a large quantity of thermal storage body.

The present invention, in an embodiment thereof, has been made in view of these problems and has an object to provide a heat or cold storage pack containing a latent thermal storage material that can be restored during transport to prolong a heat or cold storage function thereof and that exhibits a reduced temperature change in a phase transition thereof to reliably maintain the temperature of an object to be kept warm or cold in a temperature range in which the object should be kept.

Solution to Problem

To achieve the object, the present invention is arranged as follows in an embodiment thereof. The present invention, in an embodiment thereof, is directed to a heat storage pack for use in a logistic packaging container to adjust temperature of an object to be kept warm, the heat storage pack including: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept warm should be kept in such a manner that the solidification temperature is in the temperature range in which the object to be kept warm should be kept and that the onset temperature of melting is lower than an upper limit of the temperature range in which the object to be kept warm should be kept.

The present invention, in an embodiment thereof, is directed to a cold storage pack for use in a logistic packaging container to adjust temperature of an object to be kept cold, the cold storage pack including: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept cold should be kept in such a manner that a main melting temperature of the latent thermal storage material is in the temperature range in which the object to be kept cold should be kept and that the solidification temperature is higher than a lower limit of the temperature range in which the object to be kept cold should be kept.

Advantageous Effects of Invention

The present invention, in an embodiment thereof, can maintain the temperature of an object to be kept warm in the vicinity of the solidification temperature of the latent thermal storage material during a time period in which temperature is not controlled, by exploiting the latent heat released by the latent thermal storage material. In addition, because the upper limit of the temperature range in which the object to be kept warm should be kept is higher than the onset temperature of melting, the latent thermal storage material changes phase from solid to liquid and is hence restored when maintained at a temperature higher than the onset temperature of melting and lower than the upper limit during a time period in which temperature is controlled.

The present invention, in another embodiment thereof, can maintain the temperature of an object to be kept cold in the vicinity of the main melting temperature of the latent thermal storage material during a time period in which temperature is not controlled, by exploiting the latent heat released by the latent thermal storage material. In addition, because the lower limit of the temperature range in which the object to be kept cold should be kept is lower than the solidification temperature, the latent thermal storage material changes phase from liquid to solid and is hence restored when maintained at a temperature lower than the solidification temperature and higher than the lower limit during a time period in which temperature is controlled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a heat or cold storage pack in accordance with a first or second embodiment.

FIG. 2 is a conceptual drawing illustrating an example DSC thermogram and how an onset temperature of melting and a main melting temperature are determined.

FIG. 3A is a cross-sectional view of a logistic packaging container in accordance with the first or second embodiment.

FIG. 3B is a cross-sectional view of a logistic packaging container in accordance with the first or second embodiment.

FIG. 4 is a conceptual drawing illustrating how a heat or cold storage pack and a logistic packaging container in accordance with the first or second embodiment are used.

FIG. 5A is a conceptual drawing showing a temperature range achieved when a heating device is used to control temperature, in relation to a latent thermal storage material used in a logistic system in accordance with a third embodiment and a temperature range in which an article should be kept.

FIG. 5B is a conceptual drawing showing a temperature range achieved when a cooling device is used to control temperature, in relation to a latent thermal storage material used in a logistic system in accordance with the third embodiment and a temperature range in which an article should be kept.

FIG. 5C is a conceptual drawing illustrating temperature ranges for a logistic system using a conventional thermal storage material.

FIG. 6A is a conceptual drawing illustrating a manufacturing step for a heat or cold storage pack in accordance with the first or second embodiment.

FIG. 6B is a conceptual drawing illustrating manufacturing steps for a heat or cold storage pack in accordance with the first or second embodiment.

FIG. 6C is a conceptual drawing illustrating a manufacturing step for a heat or cold storage pack in accordance with the first or second embodiment.

FIG. 7 is a table listing exemplary latent thermal storage materials in accordance with Examples 2 and 3 and exemplary articles that may be transported using the thermal storage materials.

DESCRIPTION OF EMBODIMENTS

The following will define some terms used in the present application. These terms should be interpreted as defined below unless otherwise mentioned.

(1) The solidification temperature is the temperature at which a latent thermal storage material in the liquid state starts forming a crystal nucleus when maintained at constant temperature. In the present invention, the solidification temperature of a latent thermal storage material is measured using a thermocouple while lowering the temperature of a cooling container (e.g., refrigerator, freezer, or programmable thermostatic chamber) in which a plastic bottle containing the latent thermal storage material (at least 50 mL) is placed. A latent thermal storage material in the liquid phase, when placed at the solidification temperature or below, remains in the vicinity of the solidification temperature while undergoing a phase transition to solid.

(2) The onset temperature of melting is determined by extrapolating the temperature at which an endothermic peak starts toward a baseline on a DSC thermogram obtained by differential scanning calorimetry (“DSC”). FIG. 2 is a conceptual drawing illustrating an example DSC thermogram and how an onset temperature of melting and a main melting temperature are determined. A latent thermal storage material in the solid phase, when placed at the onset temperature of melting or above, starts melting.

(3) The main melting temperature is the temperature at which an endothermic peak appears on a DSC thermogram obtained by DSC. A latent thermal storage material in the solid phase, when placed at the main melting temperature or above, remains in the vicinity of the main melting temperature while undergoing a phase transition to liquid.

(4) The restoration-period temperature range for a heat storage pack is at or above the onset temperature of melting of a latent thermal storage material. Meanwhile, the restoration-period temperature range for a cold storage pack is at or below the solidification temperature of a latent thermal storage material.

(5) The restoration of a latent thermal storage material for a heat storage pack refers to the latent thermal storage material changing phase from solid to liquid as a result of being placed at or above the onset temperature of melting thereof. Meanwhile, the restoration of a latent thermal storage material for a cold storage pack refers to the latent thermal storage material changing phase from liquid to solid as a result of being placed at or below the solidification temperature thereof.

The inventors of the present invention have found, in adjusting the temperature of an object to be kept warm by using a heat storage pack containing a latent thermal storage material, that a latent thermal storage material exhibits high temperature stability in changing phase from liquid to solid if the latent thermal storage material has a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid and also found that such a latent thermal storage material can be restored if the temperature of the latent thermal storage material is controlled to be in a temperature range that is at or above the onset temperature of melting. These findings have led to the completion of the present invention.

The inventors of the present invention have accordingly made it possible to maintain the temperature of an object to be kept warm without the object having to experience large temperature changes, by exploiting the high temperature stability exhibited by the latent thermal storage material in changing phase from liquid to solid and also to prolong the heat storage function of the latent thermal storage material by restoring the latent thermal storage material during transport. The following will specifically describe an embodiment of the present invention with reference to drawings. The heat storage pack and the cold storage pack are indicated by reference numeral 100 throughout the following description because they have almost the same structures and include almost the same members and may in some cases be interchangeably used. A pack will be referred to as a heat storage pack 100 when the pack is used for the purpose of keeping an article/object warm, as a cold storage pack 100 when the pack is used for the purpose of keeping an article/object cold, and as a heat storage pack (cold storage pack) 100 when an appropriate one of the terms should be chosen in view of the intended usage of the pack. The same applies to the heat storage pack main body and the heat-storage-pack-holding section. Redundant description will be omitted.

First Embodiment Structure of Heat Storage Pack

A heat storage pack in accordance with the present invention is for use in a logistic packaging container to adjust the temperature of an object to be kept warm and includes: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material. FIG. 1 is a cross-sectional view of the heat storage pack 100 in accordance with the present embodiment. Referring to FIG. 1, the heat storage pack 100 in accordance with the present embodiment includes a housing section 120, which provides a hollow structure, inside a heat storage pack main body 110. The housing section 120 houses a thermal storage layer 130.

The heat storage pack main body 110 includes the hollow housing section 120 for housing the thermal storage layer 130. The heat storage pack main body 110 may be made of a resin material such as polyethylene, polypropylene, polyester, polyurethane, polycarbonate, polyvinyl chloride, or polyamide, a metal such as aluminum, stainless steel, copper, or silver, or an inorganic material such as glass or ceramics. The heat storage pack main body 110 is preferably made of a resin material for its durability and ease in fabricating a hollow structure. The heat storage pack main body 110 preferably has attached thereto a temperature-indicating, thermochromic sticker so that a user can estimate the temperature of the heat storage pack.

The thermal storage layer 130 contains a latent thermal storage material 150 that has a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material 150 starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material 150 starts changing phase from solid to liquid. The latent thermal storage material 150 is preferably made of a material containing organic molecules as a primary component. This composition provides extremely weak supercooling characteristics and a difference of less than 1° C. between the solidification temperature and the onset temperature of melting. When a latent thermal storage material with strong supercooling characteristics changes phase from liquid to solid, the temperature of the latent thermal storage material first drops to the solidification temperature and then rises close to the main melting temperature due to the heat generated in crystallization. The latent thermal storage material may therefore exhibit such large temperature changes that the latent thermal storage material can have a temperature beyond the temperature range in which the object to be kept warm should be kept, which renders it difficult to adjust the temperature of the latent thermal storage material. In contrast, a latent thermal storage material that has a difference of less than 1° C. between the solidification temperature and the onset temperature of melting thereof exhibits such extremely small temperature changes in a liquid-to-solid phase transition that the latent thermal storage material can remain at temperatures near the solidification temperature. The latent thermal storage material can therefore reliably maintain the temperature of the object to be kept warm in the temperature range in which the object should be kept.

Specific examples of the material of the latent thermal storage material include C₁₃-C₃₀ straight chain alkanes, C₁₃-C₂₀ straight chain alkyl alcohols, polyethylene glycols having a molecular weight of from 400 to 800, and C₁₀-C₁₄ straight chain fatty acids. These latent thermal storage materials remain near the solidification temperature for an extended period of time because the latent thermal storage materials have low thermal conductivity and slowly change phase from liquid to solid. The solidification temperature and the onset temperature of melting of these latent thermal storage materials can be precisely specified by increasing or decreasing the carbon number one by one. Correct selection of a carbon number hence enables strict temperature management. Among the C₁₃-C₃₀ straight chain alkanes, C₁₅-C₂₄ straight chain alkanes have particularly high latent heat and have a solidification temperature in the temperature range of 15 to 18° C. that is suited to maintain the temperature of chocolate, the temperature range of 20 to 25° C. that is suited to maintain the temperature of, for example, cooked rice, the temperature range of 25 to 30° C. that is suited to maintain the temperature of, for example, precision instruments and components and works of art, or the temperature range of 35 to 37° C. that is suited to maintain the temperature of, for example, blood and internal organs. Appropriate selection of a carbon number in these straight chain alkanes enables strict temperature management.

The solidification temperature of the materials described above can be precisely specified by increasing or decreasing the carbon number. Although the materials have discrete solidification temperatures, the solidification temperature of the resultant latent thermal storage material can be adjusted by mixing two or more of the materials in a proportion, which provides a continuously changing solidification temperature. Latent thermal storage materials that contain water molecules are generally difficult to use because they exhibit strong supercooling characteristics. Water-containing latent thermal storage materials can be used however if a supercooling inhibitor is added thereto in such a manner as to control the difference between the solidification temperature and the onset temperature of melting of the latent thermal storage materials to be less than 1° C. In addition, since the present embodiment exploits the liquid-to-solid phase transition of the latent thermal storage material, a latent thermal storage material is preferably selected that exhibits a suitable solidification temperature in view of the ambient temperature at which the latent thermal storage material is used. For instance, if the latent thermal storage material is going to be used in cold geographical areas where temperature drops below 0° C., a latent thermal storage material that exhibits a solidification temperature at or above 0° C. is selected for the purpose of maintaining the temperature of an object to be kept warm.

A preservative or antibacterial agent is preferably added to the material of the thermal storage layer 130. A thickening agent such as xanthan gum, guar gum, carboxy methyl cellulose, hydroxypropyl cellulose, or sodium polyacrylate may be added to the material of the thermal storage layer 130. The materials used in the present invention are not necessarily limited to the examples given above.

The latent thermal storage material 150 is selected in accordance with a desirable temperature range that is determined for each object to be kept warm. The latent thermal storage material 150 is selected so as to exhibit a solidification temperature in the desirable temperature range for preserving the object and an onset temperature of melting lower than the upper limit of the desirable temperature range for preserving the object. This selection enables the temperature to be controlled, during a time period in which temperature is controlled, to be in a temperature range in which the restoration-period temperature range overlaps the temperature range in which the object to be kept warm should be kept. The selection thereby enables the latent thermal storage material 150 to change phase from solid to liquid, hence to be restored. The latent thermal storage material 150 is preferably selected such that the latent thermal storage material 150 has a main melting temperature lower than the upper limit of the temperature range in which an object to be kept warm should be kept.

Structure of Logistic Packaging Container

FIG. 3A is a cross-sectional view of a logistic packaging container 200 in accordance with the present embodiment. The logistic packaging container 200 includes: a logistic packaging container body 210; a heat-storage-pack-holding section 220 disposed in the logistic packaging container body 210 to hold a heat storage pack; the heat storage pack 100 selected in accordance with the temperature range in which an article to be packaged should be kept; and an article housing section 230 disposed in the logistic packaging container body 210 to house the article.

The logistic packaging container body 210 includes a housing section 240 and a lid section 250. The housing section 240 has an opening through which the article and the heat storage pack 100 are taken out of, and put into, the housing section 240. The lid section 250 closes the opening. The housing section 240 and the lid section 250 may be either coupled or separated. The lid section 250 is preferably structured so as to tightly seal the opening of the housing section 240 in order to restrict the flow of heat into and out of the logistic packaging container 200.

The logistic packaging container body 210 is preferably made of a thermally insulating material such as styrene foam, urethane foam, or a vacuum insulation material. Alternatively, the logistic packaging container body 210 may include: a main body made of a material that may not be thermally insulating; and a thermal storage layer made of a thermally insulating material and disposed inside or outside the main body. The logistic packaging container body 210 may be either so sized that a person can carry it around or built with very large dimensions like, for example, a shipping container. Alternatively, the logistic packaging container body 210 may be built as a shipping container including a heating mechanism.

The heat-storage-pack-holding section 220 is disposed inside the logistic packaging container body 210. When the logistic packaging container 200 is used, the heat storage pack 100 is placed in the heat-storage-pack-holding section 220. The internal space of the logistic packaging container body 210 is hence maintained at a temperature that depends on the heat storage pack 100. The heat-storage-pack-holding section 220 may be structured so as to fix the heat storage pack 100. The heat storage pack 100 may be incorporated into the logistic packaging container body 210. The heat storage pack 100 may function as the logistic packaging container 200 on its own.

The heat storage pack 100 used in the logistic packaging container 200 is selected in accordance with the temperature range in which an article to be packaged should be kept. The heat storage pack 100 is selected such that the latent thermal storage material 150 included in the heat storage pack 100 exhibits a solidification temperature that is in the temperature range in which the article should be kept and an onset temperature of melting that is lower than the upper limit of the temperature range in which the article should be kept. This selection enables the temperature to be controlled to, during a time period in which temperature is controlled during transport, be in a temperature range in which the restoration-period temperature range overlaps the temperature range in which the object to be kept warm should be kept. The selection thereby enables the latent thermal storage material 150 to change phase from solid to liquid, hence to be restored. This arrangement can prolong the heat storage function of the latent thermal storage material 150.

In selecting a heat storage pack 100 including a latent thermal storage material 150 having the temperature range described above, the heat storage pack 100 is preferably selected such that the common control temperature (temperature setting) specified on a typical heating device (heating vehicle (heat insulation vehicle), heating warehouse (heat insulation warehouse)) used in logistics is within a range in which the restoration-period temperature range overlaps the temperature range in which the article should be kept. This particular selection allows the logistic packaging container 200 to be used in transport where a heating device is used with common temperature settings, thereby enabling flexible choice of transport routes.

The article housing section 230 is disposed inside the logistic packaging container body 210 to house an article for which the temperature range in which the article should be kept is determined. The article is hence maintained in the temperature range in which the article should be kept.

The logistic packaging container 200 may include a plurality of heat storage packs 100 as shown in FIG. 3B.

Second Embodiment

The present embodiment relates to cold storage packs. The inventors of the present invention have found, in adjusting the temperature of an object to be kept cold by using a cold storage pack containing a latent thermal storage material, that a latent thermal storage material exhibits high temperature stability in changing phase from liquid to solid if the latent thermal storage material has a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid and also found that such a latent thermal storage material can be restored if the temperature of the latent thermal storage material is controlled to be in a temperature range that is at or below the solidification temperature. These findings have led to the completion of the present invention.

The inventors of the present invention have accordingly made it possible to maintain the temperature of an object to be kept cold without the object having to experience large temperature changes in restoring the latent thermal storage material from the liquid state, by exploiting the high temperature stability exhibited by the latent thermal storage material in changing phase from liquid to solid and also to prolong the cold storage function of the latent thermal storage material by restoring the latent thermal storage material during transport. The following will specifically describe an embodiment of the present invention with reference to drawings.

Structure of Cold Storage Pack

A cold storage pack in accordance with the present invention is for use in a logistic packaging container to adjust the temperature of an object to be kept cold and includes: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material. The cold storage pack and the cold storage pack main body in accordance with the present embodiment have the same structure as the heat storage pack and the heat storage pack main body in accordance with the first embodiment, and redundant description will be omitted. A cold storage pack 100 in accordance with the present embodiment includes a housing section 120, which provides a hollow structure, inside a cold storage pack main body 110. The housing section 120 houses a thermal storage layer 130.

The thermal storage layer 130 contains a latent thermal storage material 150 that has a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material 150 starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material 150 starts changing phase from solid to liquid. The latent thermal storage material 150 is preferably made of a material composed primarily of organic molecules. This composition provides extremely weak supercooling characteristics and a difference of less than 1° C. between the solidification temperature and the onset temperature of melting. Specific examples of the material of the latent thermal storage material 150 include C₁₃-C₃₀ straight chain alkanes, C₁₃-C₂₀ straight chain alkyl alcohols, polyethylene glycols having a molecular weight of from 400 to 800, and C₁₀-C₁₄ straight chain fatty acids. Tetradecane, pentadecane, and hexadecane, which are all C₁₄-C₁₆ straight chain alkanes, are highly useful and suitable for use because these substances have high latent heat and have a main melting temperature or a solidification temperature in the chilled temperature range (2 to 8° C.) or a temperature range that is suited to preserve fresh produce (8 to 15° C.).

These materials may be mixed in any proportion, which enables adjustment of the main onset temperature of melting and the solidification temperature. Latent thermal storage materials that contain water molecules are difficult to use because they generally exhibit strong supercooling characteristics. Water-containing latent thermal storage materials can be used however if a supercooling inhibitor is added thereto in such a manner as to control the difference between the solidification temperature and the onset temperature of melting of the latent thermal storage materials to be less than 1° C. The latent thermal storage material in accordance with the present invention exhibits small temperature changes in changing phase from liquid to solid. Therefore, even if the latent thermal storage material has used up all the latent heat in keeping the object at low temperature and turned liquid, the object does not have to experience large temperature changes in restoring the latent thermal storage material. When a latent thermal storage material with supercooling characteristics is restored starting from a state in which the solid and liquid phases coexist, the solid phase, at temperatures lower than the onset temperature of melting, generally provides a nucleus growth point from which solidification can spread. Temperature hence does not change much. In contrast, when the latent thermal storage material is restored starting from a completely liquid state, solidification does not start until the material's temperature is lowered to the solidification temperature. Temperature hence changes much. In view of these facts, when a latent thermal storage material with supercooling characteristics is to be restored to keep an object at low temperature, the latent thermal storage material is used in a quantity greater than the quantity that matches a cold storage time, in order to prevent the latent thermal storage material from melting completely. In contrast, the latent thermal storage material in accordance with the present invention can be restored without causing large temperature changes even after having completely turned into liquid. The inherent latent heat can therefore be used up when an object is kept at low temperature using the latent thermal storage material. The logistic packaging container may accordingly contain the latent thermal storage material in a smaller quantity. The materials for the present invention are not necessarily limited to the examples given above.

The latent thermal storage material 150 is selected in accordance with a desirable temperature range that is determined for each object to be kept cold. The latent thermal storage material 150 is selected so as to exhibit a main melting temperature in the desirable temperature range for preserving the object and a solidification temperature higher than the lower limit of the desirable temperature range for preserving the object. This selection enables the temperature to be controlled, during a time period in which temperature is controlled, to be in a temperature range in which the restoration-period temperature range overlaps the temperature range in which the object to be kept cold should be kept. The selection thereby enables the latent thermal storage material 150 to change phase from liquid to solid, hence to be restored. Even if the latent thermal storage material 150 has used up all the latent heat in keeping the object at low temperature and turned liquid, the object can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material 150. The object to be kept cold will therefore less likely go out of the temperature range in which the object should be kept.

Structure of Logistic Packaging Container

The logistic packaging container 200 in accordance with the present embodiment includes a cold storage pack 100 in place of the heat storage pack 100 in the cross-sectional view of the logistic packaging container in accordance with the first embodiment shown in FIGS. 3A and 3B. The logistic packaging container 200 includes: a logistic packaging container body 210; a cold-storage-pack-holding section 220 disposed in the logistic packaging container body 210 to hold the cold storage pack 100; the cold storage pack 100 selected in accordance with the temperature range in which an article to be packaged should be kept; and an article housing section 230 disposed in the logistic packaging container body 210 to house the article.

The logistic packaging container body 210 may be either so sized that a person can carry it around or built with very large dimensions like, for example, a shipping container. The logistic packaging container 200 may include a cooling device like a reefer container. A reefer container can store a large quantity of articles and function as a cooling container when the reefer container is supplied with power during transport. Therefore, a reefer container is preferably used in import/export of articles where it takes a long time to transport them. Conventional reefer containers present difficulty in maintaining the temperature of articles when there is no power supply available, for example, during inspection at a customs house, which may undesirably spoil the freshness and quality of the articles. In contrast, if a reefer container is used as the logistic packaging container 200 in accordance with the present invention, the consignor needs only to place the articles and the cold storage pack 100 in accordance with the present invention in the reefer container, so that the latent thermal storage material 150 in the cold storage pack 100 in accordance with the present invention is restored when the logistic packaging container 200 is connected to a power supply and cools the articles when there is no power supply available. That enables preservation of the articles in a temperature range in which the articles should be kept. The cold storage pack 100 hence makes it possible to transport items that may lose much of their freshness and quality if placed out of a desirable temperature range, such as wine, chocolate, and fruit, for import/export, which could take an extended period of time, and to make flexible choice of transport routes.

The cold storage pack 100 used in the logistic packaging container 200 is selected in accordance with the temperature range in which an article to be packaged should be kept. The cold storage pack 100 is selected such that the latent thermal storage material 150 included in the cold storage pack 100 exhibits a main melting temperature that is in the temperature range in which the article should be kept and a solidification temperature that is higher than the lower limit of the temperature range in which the article should be kept. This selection enables the temperature to be controlled to, during a time period in which temperature is controlled during transport, be in a temperature range in which the restoration-period temperature range overlaps the temperature range in which the object to be kept cold should be kept. The selection thereby enables the latent thermal storage material 150 to change phase from liquid to solid, hence to be restored. This arrangement can prolong the cold storage function of the latent thermal storage material 150. In addition, even if the latent thermal storage material 150 has used up all the latent heat in keeping the object at low temperature and turned liquid, the object can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material 150. The object to be kept cold will therefore less likely go out of the temperature range in which the object should be kept.

In selecting a cold storage pack 100 including a latent thermal storage material 150 having the temperature range described above, the cold storage pack 100 is preferably selected such that the common control temperature (temperature setting) specified as refrigeration temperature and refrigerant temperature on a typical cooling device (e.g., refrigeration (freezer) van, refrigeration (freezer) warehouse, refrigeration (freezer) locker, or reefer container) used in logistics is within a range in which the restoration-period temperature range overlaps the temperature range in which the article should be kept. This particular selection allows the logistic packaging container 200 to be used in transport where a cooling device is used with common temperature settings, thereby enabling flexible choice of transport routes.

FIG. 4 is a conceptual drawing illustrating how the cold storage pack 100 and the logistic packaging container 200 in accordance with the present embodiment are used. When the cold storage pack 100 and the logistic packaging container 200 in accordance with the present embodiment are used, the articles and the cold storage pack 100 are packaged in the logistic packaging container 200 as shown in FIG. 4. The heat storage pack 100 and the logistic packaging container 200 in accordance with the first embodiment are used in a similar fashion.

Third Embodiment Construction of Logistic System

In a logistic system in accordance with the present embodiment, when a latent thermal storage material a liquid-to-solid phase transition of which is exploited is used as a heat storage pack, an article for which a temperature range in which the article should be kept is determined is packaged in a logistic packaging container 200 together with the heat storage pack 100 and delivered by a transporter from a consignor to a consignee. The logistic system includes a heating device that controls an external temperature of the logistic packaging container 200 to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period. The heating device heats the logistic packaging container 200 in a temperature range in which the restoration-period temperature range of the latent thermal storage material 150 used in the heat storage pack 100 overlaps the temperature range in which the article should be kept (“overlapping range”).

In a logistic system in accordance with the present embodiment, when a latent thermal storage material a solid-to-liquid phase transition of which is exploited is used as a cold storage pack, an article for which a temperature range in which the article should be kept is determined is packaged in a logistic packaging container 200 together with the cold storage pack 100 and delivered by a transporter from a consignor to a consignee. The logistic system includes a cooling device that controls an external temperature of the logistic packaging container 200 to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period. The cooling device cools the logistic packaging container 200 in a temperature range in which the restoration-period temperature range of the latent thermal storage material 150 used in the cold storage pack 100 overlaps the temperature range in which the article should be kept (“overlapping range”).

FIG. 5A is a conceptual drawing showing a temperature range achieved when the heating device is used to control temperature, in relation to the latent thermal storage material 150 used in the logistic system in accordance with the present embodiment and the temperature range in which the article should be kept. FIG. 5A shows a case where the latent thermal storage material 150 is selected so as to exhibit a solidification temperature in the temperature range in which the article should be kept and an onset temperature of melting lower than the upper limit of the temperature range in which the article should be kept. In the case shown in FIG. 5A, the temperature range achieved when the heating device is used to control temperature is lower than the upper limit of the temperature range in which the article should be kept and higher than the onset temperature of melting of the latent thermal storage material 150. The latent thermal storage material 150 can be restored by controlling temperature in such a temperature range, which can in turn prolong the heat storage function.

If there is a large difference between the solidification temperature and the onset temperature of melting, in other words, if the latent thermal storage material has strong supercooling characteristics, the temperature of the latent thermal storage material, in a liquid-to-solid phase transition, first drops to the solidification temperature and then rises to the onset temperature of melting. The latent thermal storage material may therefore exhibit such large temperature changes that the latent thermal storage material can have a temperature beyond the temperature range in which an article should be kept, which renders it difficult to exploit the liquid-to-solid phase transition. In contrast, if the difference between the solidification temperature and the onset temperature of melting is no larger than 1° C. as in the present invention, the latent thermal storage material exhibits such a small temperature change that the liquid-to-solid phase transition thereof can be exploited. The present invention is hence capable of keeping an article warm when the temperature at which the article should be kept is higher than the ambient temperature (external air temperature).

FIG. 5B is a conceptual drawing showing a temperature range achieved when a cooling device is used to control temperature, in relation to the latent thermal storage material 150 used in the logistic system in accordance with the present embodiment and the temperature range in which the article should be kept. FIG. 5B shows a case where the latent thermal storage material 150 is selected so as to exhibit a main melting temperature in the temperature range in which the article should be kept and a solidification temperature higher than the lower limit of the temperature range in which the article should be kept. In the case shown in FIG. 5B, the temperature range achieved when the cooling device is used to control temperature is higher than the lower limit of the temperature range in which the article should be kept and lower than the solidification temperature of the latent thermal storage material 150. The latent thermal storage material 150 can be restored by controlling temperature in such a temperature range, which can in turn prolong the cold storage function of the latent thermal storage material 150. In addition, even if the latent thermal storage material 150 has used up all the latent heat in keeping the article at low temperature and turned liquid, the object to be kept cold can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material. The object to be kept cold will therefore less likely go out of the temperature range in which the object should be kept.

Since the difference between the solidification temperature and the onset temperature of melting is no larger than 1° C., and the latent thermal storage material 150 does not exhibit large temperature changes in the phase transition, the latent thermal storage material 150 can reliably keep articles at low temperature and be restored in the transport of such an article that the temperature range in which the article should be kept is narrow, for example, chocolate, which should be kept at 15 to 18° C., and fruit such as strawberries, which should be kept at 1 to 2° C. Additionally, the temperature range in which the temperature range in which the article should be kept overlaps the restoration period broadens. Therefore, the cooling device does not need to strictly control temperature, and the latent thermal storage material 150 can be restored even if the upper limit of the temperature range controlled by the cooling device rises close to the solidification temperature. That in turn will help reduce the cost of the cooling device and save energy.

The heating or cooling device may not continuously control temperature in the overlapping range in each time period in which the heating or cooling device controls temperature and may not control temperature in the overlapping range every time the heating or cooling device controls temperature, for the following reasons. If the heating or cooling device only intermittently controls temperature in the overlapping range, the logistic system can still restore the latent thermal storage material 150 when the heating or cooling device controls temperature in the overlapping range, which in turn can prolong the heat or cold storage function of the latent thermal storage material 150.

FIG. 5C is a conceptual drawing illustrating temperature ranges for a logistic system using a conventional thermal storage material. Referring to FIG. 5C, logistic systems using a conventional thermal storage material have paid attention to the temperature range provided by the thermal storage material and the control temperature at the hubs, in relation to the temperature range in which the article should be kept. No logistic systems using a conventional thermal storage material have however paid attention to relationships between thermal storage materials and control temperatures at the hubs.

In the logistic system in accordance with the present embodiment, the latent thermal storage material 150 used in the heat storage pack 100 is selected such that the onset temperature of melting is lower than the upper limit of the temperature range in which the article should be kept. If the latent thermal storage material 150 is further selected such that the main melting temperature is also lower than the upper limit of the temperature range in which the article should be kept, the heat storage pack 100 may be used also as a cold storage pack 100, depending on the ambient temperature.

Specific examples are given next. Assume, as an example, that the latent thermal storage material 150 has the solidification temperature thereof controlled to be 16° C., the onset temperature of melting controlled to be 16° C., and the main melting temperature controlled to be 17° C. in a temperature range (for example, 15 to 18° C.) that is suited to maintain the temperature of chocolate. Under these conditions, if the ambient temperature is 15° C. or lower, the latent thermal storage material 150 may be caused to turn liquid at 16 to 18° C. for use as the heat storage pack 100. Meanwhile, if the ambient temperature is 18° C. or higher, the latent thermal storage material 150 may be caused to turn solid at 15 to 16° C. for use as the cold storage pack 100. The heating and cooling devices are also modified in accordance with purposes.

Method of manufacturing heat storage pack and cold storage pack A description will be given next of a method of manufacturing the heat storage pack (cold storage pack) 100 in accordance with the present embodiment. FIGS. 6A to 6C are conceptual drawings illustrating manufacturing steps for the heat storage pack 100 in accordance with the present embodiment. First, as shown in FIG. 6A, a heat storage pack main body (cold storage pack main body) 110 is prepared that includes a hollow structure. The heat storage pack main body 110 preferably has an injection hole 170 through which the latent thermal storage material 150 can be injected. Next, the latent thermal storage material 150 is injected. The latent thermal storage material 150 may be injected by any method and is preferably injected using a cylinder pump or a Mohno pump. FIG. 6B shows an example using a cylinder pump. Referring to FIG. 6B, an injection hose of a cylinder pump is attached to the injection hole 170 of the heat storage pack main body 110, and a sucking hose of the cylinder pump is attached to the container containing the latent thermal storage material 150. Next, the latent thermal storage material 150 is sucked up by lowering a piston of the cylinder pump, to pour the thermal storage material into the piston. The piston is then lifted to inject the latent thermal storage material 150 into the heat storage pack main body 110.

Then, as shown in FIG. 6C, the injection hole 170 of the heat storage pack main body 110 is closed using a plug 190. The plug 190 may seal the injection hole 170 by a conventional technique such as ultrasonic welding or thermal welding and may be a screw plug for the user to freely open/close the hole by hand. Ultrasonic or thermal welding-based sealing is preferable to inhibit the latent thermal storage material 150 from leaking.

Finally, when the pack 100 is to be used as the heat storage pack 100, the heat storage pack is left in an ambient temperature higher than the onset temperature of melting of the latent thermal storage material 150, to retain the heat storage pack in the liquid phase. On the other hand, when the pack 100 is to be used as the cold storage pack 100, the cold storage pack 100 is left at an ambient temperature not higher than the solidification temperature of the latent thermal storage material 150, to solidify the latent thermal storage material 150. The heat storage pack 100 or the cold storage pack 100 in accordance with the present embodiment is manufactured by these steps. The technical scope of the present invention is not necessarily limited to these embodiments and may be modified in various ways without departing from the scope of the present invention.

Example 1

Example 1 relates to a logistic system using a heat storage pack in accordance with the first embodiment. Example 1 assumes a logistic system for transporting, for example, cooked rice, which should be maintained in a temperature range of 20 to 25° C., from a food manufacturer (i.e., consignor) to a shop (i.e., consignee) in an environment where air temperature is 10° C. First, the consignor packaged cooked rice and a heat storage pack containing a latent thermal storage material (liquid state) containing heptadecane as a main component in a logistic packaging container shown in FIGS. 3A and 3B in a food manufacturing factory where the ambient temperature is 25° C. The heat storage pack had been manufactured by preparing a blow-molded container (cold storage pack main body) shown in FIG. 6A made of polyethylene with dimensions of 180×280×29 mm/t, injecting a liquid latent thermal storage material (800 grams) using a liquid injector that is a blow-molded container equipped with a cylinder pump shown in FIG. 6B, capping the injection hole using an ultrasonic welder, and sealing the injection hole by welding.

The latent thermal storage material had a solidification temperature of 21° C., an onset temperature of melting of 21° C., and a main melting temperature of 22° C. The solidification temperature differed from the onset temperature of melting by less than 1° C. and was in the temperature range in which cooked rice should be kept. The solidification temperature of the latent thermal storage material was the temperature at which the latent thermal storage material (50 mL) in a plastic bottle starts forming a crystal nucleus in a programmable thermostatic chamber when cooled to −20° C. The onset temperature of melting and the main melting temperature were evaluated by differential scanning calorimetry (instrument used: Rigaku DSC 8213, temperature range measured: −30 to 30° C., cooling rate: −5° C./min, heating rate: 5° C./min).

The logistic packaging container was transported to a dispatch center in an ambient truck in an environment where air temperature was 10° C., which took 2 hours. The temperature inside the dispatch center was 25° C. The delivery was unpacked and sorted, taking 1 hour. It was found upon arrival at the dispatch center that the latent thermal storage material in the logistic packaging container had partly solidified. An hour later when the sorting was completed, however, it was found that the latent thermal storage material had turned back liquid, that is, the latent thermal storage material had been restored from solid to liquid. Next, the restored heat storage pack and the sorted cooked rice were packaged in a logistic packaging container and transported to a shop, which took 2 hours. The delivery was unpacked, and it was found that the quality of the cooked rice was retained and also that the latent thermal storage material in the heat storage pack had partly solidified. These results show that the latent thermal storage material in accordance with the present invention is restored while the delivery is staying at the dispatch center. The logistic system in accordance with the present invention thereby eliminates the need to replace the heat storage pack at the dispatch center and hence allows long-time transport. Since the latent thermal storage material in accordance with the present invention is restored while the delivery is staying at the dispatch center, the logistic system in accordance with the present invention reduces the weight of the packaged latent thermal storage material used.

Examples 2 and 3

FIG. 7 lists exemplary latent thermal storage materials used in cold storage packs in accordance with Examples 2 and 3 and exemplary articles that may be transported using the thermal storage materials. The table shows restoration-period temperature ranges that the latent thermal storage materials exhibit when the latent thermal storage materials are used in cold storage packs. Suitable selection from latent thermal storage materials with various main melting temperatures like the examples shown in the table enables transport of various articles with the temperature thereof maintained in the temperature range in which the articles should be kept, without having to replacing the latent thermal storage material during transport. In addition, since the difference between the solidification temperature and the onset temperature of melting is no larger than 1° C., articles that should be kept in a narrow temperature range such as medicines and chocolate can find a temperature range in which the restoration-period temperature range overlaps a temperature range in which the articles should be kept. Therefore, the cold storage pack can be used over an extended period of time.

The present invention, in an embodiment thereof, may be arranged as follows. (1) The present invention, in an embodiment thereof, is directed to a heat storage pack for use in a logistic packaging container to adjust temperature of an object to be kept warm, the heat storage pack including: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept warm should be kept in such a manner that the solidification temperature is in the temperature range in which the object to be kept warm should be kept and that the onset temperature of melting is lower than an upper limit of the temperature range in which the object to be kept warm should be kept.

These features enable the temperature of the object to be kept warm to be maintained in the vicinity of the solidification temperature without the object having to experience large temperature changes during a time period in which temperature is not controlled, by exploiting the latent heat released by the latent thermal storage material which exhibits high temperature stability in a liquid-to-solid phase transition. In addition, because the upper limit of the temperature range in which the object to be kept warm should be kept is higher than the onset temperature of melting, the latent thermal storage material changes phase from solid to liquid and is hence restored to exhibit a prolonged heat storage function, by heating the latent thermal storage material at a temperature higher than the onset temperature of melting and lower than the upper limit during a time period in which temperature is controlled.

(2) In a heat storage pack in accordance with an embodiment of the present invention, the latent thermal storage material includes either a C₁₃-C₃₀ straight chain alkane or a C₁₃-C₂₀ straight chain alkyl alcohol.

The latent thermal storage material has low thermal conductivity and slowly changes phase from liquid to solid. The use of such a latent thermal storage material enables the object to be kept in the vicinity of the solidification temperature for an extended period of time and also enables strict temperature management.

(3) In a heat storage pack in accordance with an embodiment of the present invention, the latent thermal storage material includes a C₁₅-C₂₄ straight chain alkane.

The latent thermal storage material has low thermal conductivity and slowly changes phase from liquid to solid. The use of such a latent thermal storage material enables the object to be kept in the vicinity of the solidification temperature for an extended period of time, which makes it possible to maintain the temperature of, for example, chocolate, cooked rice, precision instruments and components, and works of art, as well as blood and internal organs, and also enables strict temperature management.

(4) The present invention, in an embodiment thereof, is directed to a logistic packaging container in which an article is packaged, the logistic packaging container including: a logistic packaging container body; the heat storage pack described in any one of (1) to (3), the heat storage pack being selected in accordance with a temperature range in which the article to be packaged should be kept; a heat-storage-pack-holding section provided inside the logistic packaging container body to hold the heat storage pack; and an article housing section provided inside the logistic packaging container body to house the article.

These features provide, for use in logistics, a heat storage pack containing a latent thermal storage material that exhibits high temperature stability in a liquid-to-solid phase transition.

(5) The present invention, in an embodiment thereof, is directed to a logistic system where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container described in (4) and delivered by a transporter from a consignor to a consignee, the logistic system including: a heating device configured to control an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the heating device heats the logistic packaging container at a temperature higher than the onset temperature of melting of the latent thermal storage material and lower than an upper limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from solid to liquid.

These features enable the temperature of an article to be maintained in the vicinity of the solidification temperature of a latent thermal storage material in a logistic system in which a logistic packaging container containing the latent thermal storage material is used. The features also enable restoration of the latent thermal storage material, thereby prolonging the heat storage function of the latent thermal storage material.

(6) The present invention, in an embodiment thereof, is directed to a logistic method where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container described in (4) and delivered by a transporter from a consignor to a consignee, the logistic method including controlling, by using a heating device, an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the heating device heats the logistic packaging container at a temperature higher than the onset temperature of melting of the latent thermal storage material and lower than an upper limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from solid to liquid.

These features enable the temperature of an article to be maintained in the vicinity of the solidification temperature of a latent thermal storage material in a logistic method in which a logistic packaging container containing the latent thermal storage material is used. The features also enable restoration of the latent thermal storage material, thereby prolonging the heat storage function of the latent thermal storage material.

(7) The present invention, in an embodiment thereof, is directed to a cold storage pack for use in a logistic packaging container to adjust temperature of an object to be kept cold, the cold storage pack including: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept cold should be kept in such a manner that a main melting temperature of the latent thermal storage material is in the temperature range in which the object to be kept cold should be kept and that the solidification temperature is higher than a lower limit of the temperature range in which the object to be kept cold should be kept.

These features enable the temperature of the object to be kept cold to be maintained in the vicinity of the main melting temperature during a time period in which temperature is not controlled, by exploiting the latent heat released by the latent thermal storage material. In addition, because the lower limit of the temperature range in which the object to be kept cold should be kept is lower than the solidification temperature, the latent thermal storage material changes phase from liquid to solid and is hence restored to exhibit a prolonged cold storage function when maintained at a temperature lower than the solidification temperature of the latent thermal storage material and higher than the lower limit of the temperature range in which the object to be kept cold should be kept during a time period in which temperature is controlled. Additionally, even if the latent thermal storage material has used up all the latent heat in keeping the object at low temperature and turned liquid, the object to be kept cold can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material, by exploiting the high temperature stability exhibited by the latent thermal storage material in a liquid-to-solid phase transition.

(8) In a cold storage pack in accordance with an embodiment of the present invention, the latent thermal storage material includes either a C₁₃-C₃₀ straight chain alkane or a C₁₃-C₂₀ straight chain alkyl alcohol.

The use of such a latent thermal storage material enables the object to be kept at low temperature without the object having to experience large temperature changes in restoring the latent thermal storage material and also enables strict temperature management.

(9) In a cold storage pack in accordance with an embodiment of the present invention, the latent thermal storage material includes a C₁₄-C₁₆ straight chain alkane.

The use of such a latent thermal storage material enables the object to be kept in the highly useful chilled temperature range (2 to 8° C.) and a temperature range that is suited to preserve fresh produce (8 to 15° C.) and also enables strict temperature management.

(10) The present invention, in an embodiment thereof, is directed to a logistic packaging container in which an article is packaged, the logistic packaging container including: a logistic packaging container body; the cold storage pack described in any one of (7) to (9), the cold storage pack being selected in accordance with a temperature range in which the article to be packaged should be kept; a cold-storage-pack-holding section provided inside the logistic packaging container body to hold the cold storage pack; and an article housing section provided inside the logistic packaging container body to house the article.

These features provide, for use in logistics, a cold storage pack containing a latent thermal storage material that exhibits high temperature stability in a liquid-to-solid phase transition.

(11) The present invention, in an embodiment thereof, is directed to a logistic system where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container described in (10) and delivered by a transporter from a consignor to a consignee, the logistic system including: a cooling device configured to control an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the cooling device cools the logistic packaging container at a temperature lower than the solidification temperature of the latent thermal storage material and higher than a lower limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from liquid to solid.

These features enable the latent thermal storage material to be restored in a logistic system in which a logistic packaging container containing the latent thermal storage material is used, thereby prolonging the cold storage function of the latent thermal storage material. In addition, even if the latent thermal storage material has used up all the latent heat in keeping the object at low temperature and turned liquid, the object can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material.

(12) The present invention, in an embodiment thereof, is directed to a logistic method where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container described in (10) and delivered by a transporter from a consignor to a consignee, the logistic method including controlling, by using a cooling device, an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the cooling device cools the logistic packaging container at a temperature lower than the solidification temperature of the latent thermal storage material and higher than a lower limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from liquid to solid.

These features enable the latent thermal storage material to be restored in a logistic method in which a logistic packaging container containing the latent thermal storage material is used, thereby prolonging the cold storage function of the latent thermal storage material. In addition, even if the latent thermal storage material has used up all the latent heat in keeping the object at low temperature and turned liquid, the object can be kept at low temperature without having to experience large temperature changes in restoring the latent thermal storage material.

The present international application hereby claims priority to Japanese Patent Application No. 2017-063250 filed 28 Mar. 2017, the entire contents of which are incorporated herein by reference.

REFERENCE SIGNS LIST

-   100 Heat storage pack, Cold Storage pack -   110 Heat storage pack Main Body, Cold Storage pack Main Body -   120 Housing Section -   130 Thermal Storage Layer -   150 Latent thermal storage material -   170 Injection Hole -   190 Plug -   200 Logistic Packaging Container -   210 Logistic Packaging Container Body -   220 Heat-storage-pack-holding Section, Cold-storage-pack-holding     Section -   230 Article Housing Section -   240 Housing Section -   250 Lid Section 

1.-12. (canceled)
 13. A logistic system where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container and delivered by a transporter from a consignor to a consignee, the logistic system comprising: a heating device configured to control an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the logistic packaging container comprising: a logistic packaging container body; the heat storage pack to adjust temperature of an object to be kept warm, the heat storage pack being selected in accordance with a temperature range in which the article to be packaged should be kept; a heat-storage-pack-holding section provided inside the logistic packaging container body to hold the heat storage pack; and an article housing section provided inside the logistic packaging container body to house the article, the heat storage pack comprising: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept warm should be kept in such a manner that the solidification temperature is in the temperature range in which the object to be kept warm should be kept and that the onset temperature of melting is lower than an upper limit of the temperature range in which the object to be kept warm should be kept and the heating device heats the logistic packaging container at a temperature higher than the onset temperature of melting of the latent thermal storage material and lower than an upper limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from solid to liquid.
 14. The logistic system according to claim 13, wherein the latent thermal storage material includes either a C₁₃-C₃₀ straight chain alkane or a C₁₃-C₂₀ straight chain alkyl alcohol.
 15. The logistic system according to claim 13, wherein the latent thermal storage material includes a C₁₅-C₂₄ straight chain alkane.
 16. A logistic system where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container and delivered by a transporter from a consignor to a consignee, the logistic system comprising: a cooling device configured to control an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the logistic packaging container comprising: a logistic packaging container body; the cold storage pack to adjust temperature of an object to be kept cold, the cold storage pack being selected in accordance with a temperature range in which the article to be packaged should be kept; a cold-storage-pack-holding section provided inside the logistic packaging container body to hold the cold storage pack; and an article housing section provided inside the logistic packaging container body to house the article, the cold storage pack comprising: a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid; and a housing section configured to house the latent thermal storage material, wherein the latent thermal storage material is selected in accordance with a temperature range in which the object to be kept cold should be kept in such a manner that a main melting temperature of the latent thermal storage material is in the temperature range in which the object to be kept cold should be kept and that the solidification temperature is higher than a lower limit of the temperature range in which the object to be kept cold should be kept and the cooling device cools the logistic packaging container at a temperature lower than the solidification temperature of the latent thermal storage material and higher than a lower limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from liquid to solid.
 17. The logistic system according to claim 16, wherein the latent thermal storage material includes either a C₁₃-C₃₀ straight chain alkane or a C₁₃-C₂₀ straight chain alkyl alcohol.
 18. The logistic system according to claim 16, wherein the latent thermal storage material includes a C₁₄-C₁₆ straight chain alkane.
 19. A logistic method where the article, for which the temperature range in which the article should be kept is determined, is packaged in the logistic packaging container and delivered by a transporter from a consignor to a consignee, the logistic method comprising: adjusting, to the temperature range where the article should be held, by using a latent thermal storage material having a difference of less than 1° C. between a solidification temperature at which the latent thermal storage material starts changing phase from liquid to solid and an onset temperature of melting at which the latent thermal storage material starts changing phase from solid to liquid, controlling, by using a heating device or a cooling device, an external temperature of the logistic packaging container to be in the temperature range in which the article should be kept either before or after a time period in which temperature is not controlled or both before and after the time period, wherein the heating device heats the logistic packaging container at a temperature higher than the onset temperature of melting of the latent thermal storage material and lower than an upper limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from solid to liquid or the cooling device cools the logistic packaging container at a temperature lower than the solidification temperature of the latent thermal storage material and higher than a lower limit of the temperature range in which the article should be kept, so that the latent thermal storage material changes phase from liquid to solid.
 20. The logistic method according to claim 19, wherein the latent thermal storage material includes either a C₁₃-C₃₀ straight chain alkane or a C₁₃-C₂₀ straight chain alkyl alcohol.
 21. The logistic method according to claim 19, wherein the latent thermal storage material includes a C₁₄-C₁₆ straight chain alkane. 